What is the ruling on smashing eggs on car tires in the belief that it protects them from the evil eye and envy, and does this act affect the soundness of one's creed?

Breaking eggs, sprinkling salt, or sacrificing an animal to ward off the evil eye or jinn are acts of pre-Islamic ignorance (Jahiliyyah) that are forbidden and constitute shirk (polytheism), because Allah has not made them a legitimate or customary means of repelling the evil eye or the harm of jinn. This act is considered minor shirk, and it may become major shirk if it is intended to draw closer to the jinn or if it is believed that the means itself repels harm. The evil eye must be warded off through legitimate means, such as reciting the Qur'an and performing adhkar (remembrances of Allah).